What are you talking about? Of course they have agency. They're using that agency to funnel as much money as possible into their pockets, and away from other people, it's not that they can't imagine anything different, it's that when they do what they see is a world in which they're not as well off.

That's a very naive take - but also a popular one, because it gives people license to hate those who seem to be better off.

The truth is, no one just acquires power on their own - people with power have it because other people let them, and they can wield this power only as long, and only in ways, as others allow it. Gaining power doesn't make one more free to exercise it - on the contrary, the more power you have, the more constrained you are by interests of those who provide you that power.